Can HFNC Cause Pneumothorax?
Yes, HFNC can cause pneumothorax, though this is a rare complication occurring in approximately 1-2% of patients, primarily through barotrauma from the positive end-expiratory pressure (PEEP) generated by high flow rates.
Mechanism of Pneumothorax with HFNC
HFNC generates positive end-expiratory pressure in the upper airways by delivering flows up to 50-60 L/min, which facilitates alveolar recruitment but can also create distending pressure similar to nasal continuous positive airway pressure 1. This PEEP effect, while beneficial for oxygenation, carries the risk of barotrauma when excessive pressure damages alveoli and causes air leaks 2, 3.
The risk is particularly elevated when flow rates exceed the patient's minute ventilation, as this increases the likelihood of pressure-related alveolar damage 4.
Documented Cases and Incidence
- Pediatric populations show pneumothorax rates of 1-2% in ICU settings, with some cases requiring chest tube insertion 5
- Adult case reports document pneumothorax occurring 4 days after HFNC initiation at 40 L/min, accompanied by subcutaneous emphysema and pneumomediastinum 2
- COVID-19 patients on HFNC have developed spontaneous pneumothorax, though the viral pneumonia itself contributes to this risk independent of HFNC 6
- A nationwide German survey found that 17.9% of pediatric clinics reported observing severe complications including pneumothorax with HFNC use 3
High-Risk Clinical Scenarios
Patients at increased risk for HFNC-related pneumothorax include:
- Those receiving flow rates >40 L/min or flows exceeding their minute ventilation 2, 4
- Patients with underlying lung disease causing alveolar fragility (ARDS, severe pneumonia, COVID-19) 2, 6
- Immunocompromised patients with hemophagocytic lymphohistiocytosis or similar conditions 2
- Pediatric patients, particularly when HFNC is used off-label for positive pressure support 4
Critical Monitoring Requirements
To detect pneumothorax early, monitor for:
- New-onset dyspnea or worsening hypoxemia during HFNC therapy 2
- Decreased breath sounds, hyperresonance to percussion, or subcutaneous emphysema on examination 2
- Reassess patients 30-60 minutes after initiating HFNC and continuously thereafter for signs of respiratory deterioration 7, 8
- Obtain chest imaging if clinical deterioration occurs, as pneumothorax may be accompanied by pneumomediastinum 2, 4
Management When Pneumothorax Occurs
Immediate cessation of HFNC is required when pneumothorax develops 2. In the documented adult case, respiratory condition improved after stopping HFNC 2. Chest tube placement is necessary for clinically significant pneumothoraces 5, 4.
Balancing Risk Against Benefit
Despite this complication risk, the 2022 European Respiratory Society guidelines recommend HFNC over conventional oxygen therapy in hypoxemic acute respiratory failure because it reduces intubation rates (risk ratio 0.89), improves patient comfort significantly, and does not increase mortality 1. The pneumothorax risk must be weighed against HFNC's benefits of avoiding ventilator-associated complications like pneumonia, which carry higher morbidity and mortality 1.
HFNC should be used within ICU or intermediate care settings where continuous monitoring can detect complications promptly 3. Escalate to NIV or intubation immediately if HFNC fails rather than prolonging inadequate support, as delayed intubation worsens mortality 7, 8.